Magnesium oxide particles, as being lightweight and having excellent properties of heat resistance, heat conductivity, and electric insulation, are useful as a heat-resistant material or heat-dissipating filler. In particular, the particles have excellent properties as heat-dissipating filler which, when added to resin or the like, improves the heat conductivity of the resin product. Hence, the particles are used as filler for a molded body, an adhesive, grease or the like.
Such a molding body, an adhesive, grease, or the like, each containing magnesium oxide, is used as, for example, a printed circuit board on which electronic components (e.g. semiconductor element) are to be mounted, an electronic component, an adhesive for producing an electronic device (e.g. printed circuit board on which electronic components are mounted), or grease to be applied to an electronic component for improvement of heat dissipation of the electronic component.
Components containing magnesium oxide with high heat conductivity, such as an electronic component and a printed circuit board, exhibit improved heat dissipation. Magnesium oxide can prevent an excessive increase in the temperature of electronic components when heat is generated by the electronic components, and can prevent malfunction of the electronic components or deterioration of the resin used for the electronic components.
Patent Literature 1 discloses production of such magnesium oxide particles in order to provide high filling for a resin and to increase the heat dissipation. Here, magnesium oxide whose primary particles are spherical is produced by preparing magnesium hydroxide containing acetate in a predetermined proportion, and calcining the magnesium hydroxide at a predetermined temperature.
Patent Literature 2 teaches magnesium oxide that exhibits a ratio (median diameter)/(specific surface diameter calculated from specific surface area) of 3 or less, a ratio D90/D10 of 4 or less, a sharp particle size distribution, and a controlled degree of aggregation. Patent Literature 3 discloses use of magnesium oxide as filler for a resin composition or grease, for example.